大负荷承载螺栓的超声波探伤技术研究

发布时间：2018-04-26 23:16

本文选题：大负荷承载螺栓 + 探伤系统　；参考：《沈阳理工大学》2017年硕士论文

【摘要】：大负荷承载螺栓常用作风力发电机、桥梁、汽轮机等系统的关键紧固件。在长时间的设备运行中,由于温度变化及高应力的作用,螺栓容易产生蠕变、疲劳变形等问题;进而会导致螺栓产生局部裂纹,严重时会产生断裂,严重危及设备和人员安全,因此加强对大负荷承载螺栓的无损探伤检测意义重大。超声波探伤具有穿透能力强、方向性好、能量高、对人体无害等特点,应用于大负荷承载螺栓的缺陷检测是可行的。论文针对大负荷承载螺栓进行了超声波检测关键技术的研究。分析了螺栓常见的缺陷以及缺陷产生原因,确定了大负荷承载螺栓的探伤方法,设计了螺栓数字化超声波探伤系统。螺栓常见的问题是设备运行一段时间后,螺栓出现了内部裂纹及断裂,这种裂纹或断裂主要由不同大小及角度的横向力与纵向力长期作用产生的。对螺栓缺陷的探伤方法采用直探头、斜探头脉冲反射法。螺栓数字化超声波探伤系统由上位机、下位机两部分组成;上位机通过VB6.0操作界面实现人机界面对话,完成螺栓的探伤缺陷判断及处理;下位机则包含超声波探伤系统发射模块、接收模块、6MHz数据采集模块,由发射模块产生超声波,超声波发射至螺栓内部产生回波信号,接收模块对回波信号进行处理,处理后的信号进入数据采集模块;采用USB通讯协议进行上位机与下位机之间数据传输。本课题以大负荷承载螺栓为对象,实验过程中分别针对应用试块及螺栓进行了系统校准、分辨力检测、盲区检测等实验,准确的对试块及螺栓人工缺陷定性及检测,验证了超声波探伤检测系统对螺栓内部缺陷检测的可行性。
[Abstract]:Large load bearing bolts are often used as key fasteners for wind turbines, bridges, steam turbines and so on. During the operation of the equipment for a long time, because of the change of temperature and the effect of high stress, the bolts are prone to creep, fatigue deformation and other problems, which will lead to the local cracks of the bolts, which will break seriously and endanger the safety of the equipment and personnel seriously. Therefore, it is of great significance to strengthen the non-destructive testing of load-bearing bolts. Ultrasonic flaw detection has the characteristics of strong penetration, good directivity, high energy, harmless to human body, etc. It is feasible to apply it to the defect detection of heavy load bearing bolt. In this paper, the key technology of ultrasonic testing for large load bearing bolt is studied. This paper analyzes the common defects of bolts and the causes of the defects, determines the method of flaw detection for large load bearing bolts, and designs a digital ultrasonic flaw detection system for bolts. The common problem of bolt is that after the equipment runs for a period of time, the bolt appears internal crack and fracture, this kind of crack or fracture is mainly caused by the long-term action of transverse force and longitudinal force of different sizes and angles. Direct probe and oblique probe pulse reflection are used to detect bolt defects. The bolt digital ultrasonic flaw detection system is composed of two parts: upper computer and lower computer. The upper computer realizes man-machine interface dialogue through VB6.0 operation interface, and accomplishes the judgment and treatment of bolt flaw detection. The lower computer includes the ultrasonic flaw detection system transmitting module, the receiving module is 6MHz data acquisition module, the ultrasonic wave is generated by the transmitting module, the ultrasonic wave signal is generated from the inside of the bolt, and the receiving module processes the echo signal. The processed signals enter the data acquisition module, and the USB communication protocol is used to transmit the data between the upper computer and the lower computer. In the course of the experiment, the system calibration, resolution test, blind zone detection and so on are carried out for the application test blocks and bolts, and the artificial defects of the test blocks and bolts are accurately identified and detected. The feasibility of ultrasonic flaw detection system is verified.
【学位授予单位】：沈阳理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG115.285

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